Search Results (352)

Background: This study aimed to examine the effects of an 8-week plyometric training program on lower-limb explosive strength, jump performance, musculotendinous stiffness, reactive strength index (RSI), and multidirectional speed in elite Polish badminton players. Methods: Twenty-four athletes were randomly assigned to either an experimental group (n = 15), which supplemented their regular badminton training with plyometric exercises, or a control group (n = 15), which continued standard technical training. Performance assessments included squat jump (SJ), countermovement jump (CMJ), single-leg jumps, sprint tests (5 m, 10 m), lateral movements, musculotendinous stiffness, and RSI measurements. Results: The experimental group showed statistically significant improvements in jump height, power output, stiffness, and 10 m sprint and lateral slide-step performance (p < 0.05), with large effect sizes. No significant changes were observed in the control group. Single-leg jump improvements suggested potential benefits for addressing lower-limb asymmetries. Conclusions: An 8-week plyometric intervention significantly enhanced lower-limb explosive performance and multidirectional movement capabilities in young badminton players. These findings support the integration of targeted plyometric training into regular training programs to optimize physical performance, improve movement efficiency, and potentially reduce injury risk in high-intensity racket sports. Full article

To enable the practical application of passive back-support exoskeletons employing pneumatic artificial muscles (PAMs) in tasks such as agricultural work, we evaluated their assistive effectiveness in a half-squatting posture with a staggered stance. In this context, assistive force profiles were adjusted according to body posture to achieve more effective support. The targeted assistive force profile was designed to be continuously active from the standing to the half-squatting position, with minimal variation across this range. The assistive force profile was developed based on a PAM contractile force model and implemented using a cam mechanism. The effectiveness of assistance was assessed by measuring body flexion angles and erector spinae muscle activity during lifting and carrying tasks. The results showed that the assistive effect was greater on the side with the forward leg. Compared to the condition without exoskeleton assistance, the conventional pulley-based system reduced muscle activity by approximately 20% whereas the cam-based system achieved a reduction of approximately 30%. Full article

The mental and physical health of college students, especially in urban environments like Shanghai, is crucial given the high academic and urban stressors, which were intensified by the COVID-19 lockdown. Prior research has shown gender differences in health impacts during public health crises, with females often more vulnerable to mental health issues. Objective: This study aimed to comprehensively assess the physical and psychological health of Chinese college students post-lockdown, focusing on the relationship between stress, anxiety, depression, sleep patterns, and physical health, with a particular emphasis on gender differences. Methods: We conducted a cross-sectional study involving 116 students in Shanghai, utilizing psychological scales (HAMA, IPAQ, PSQI, SDS, FS 14, PSS, SF-36) and physical fitness tests (resting heart rate, blood pressure, hand grip, forced vital capacity, standing long jump, sit-and-reach, one-minute sit-up test and the one-minute squat test, single-leg stand test with eyes closed), to analyze health and behavior during the pandemic lockdown. All students have undergone the same life habits during the pandemic. Results: The HAMA scores indicated no significant levels of physical or mental anxiety. The PSS results (42.45 ± 8.93) reflected a high overall stress level. Furthermore, the PSQI scores (5.4 ± 2.91) suggested that the participants experienced mild insomnia. The IPAQ scores indicated higher levels of job-related activity (1261.49 ± 2144.58), transportation activity (1253.65 ± 987.57), walking intensity (1580.78 ± 1412.20), and moderate-intensity activity (1353.03 ± 1675.27) among college students following the lockdown. Hand grip strength (right) (p = 0.001), sit-and-reach test (p = 0.001), standing long jump (p = 0.001), and HAMA total score (p = 0.033) showed significant differences between males and females. Three principal components were identified in males: HAMA, FS14, and PSQI, explaining a total variance of 70.473%. Similarly, three principal components were extracted in females: HAMA, PSQI, and FS14, explaining a total variance of 69.100%. Conclusions: Our study underscores the complex interplay between physical activity (PA), mental health, and quality of life, emphasizing the need for gender-specific interventions. The persistent high stress, poor sleep quality, and reduced PA levels call for a reorganized teaching schedule to enhance student well-being without increasing academic pressure. Full article

Background/Objectives: This study aims to investigate the effects of caffeinated chewing gum on maximal strength, muscular power, and neural drive to the prime movers during bench press and back squat in resistance-trained men. Methods: Sixteen resistance-trained males participated in a double-blind, randomized trial, chewing either caffeinated gum (4 mg/kg) or placebo gum on two separate occasions, seven days apart. After chewing for 5 min, participants performed a maximal strength test followed by muscular power assessments at 25%, 50%, 75%, and 90% of their one-repetition maximum (1RM), completing with 3, 2, 1, and 1 repetition (s), respectively, for bench press and back squat. Surface electromyography data were recorded for each repetition. Results: Caffeinated gum did not significantly improve one-repetition maximum (1RM) for bench press (p > 0.05), but increased mean frequency (MF) and median frequency (MDF) in anterior deltoid, pectoralis major, and biceps brachii (all p < 0.05) compared to placebo. For back squat, 1RM increased with caffeinated gum, along with higher MF and MDF in vastus medialis (all p < 0.05). Caffeinated gum also improved mean and peak velocities, and mean and peak power outputs at 25–75% 1RM during the bench press (all p < 0.05), along with elevated MDF in pectoralis major and biceps brachii (all p < 0.05). Similar improvements were seen in mean and peak velocities during the back squat at 25–90% 1RM (all p < 0.05), along with higher MF and MDF in vastus medialis and increased normalized root mean square activity in gluteus maximus (all p < 0.05). Conclusions: Caffeinated chewing gum (4 mg/kg) enhanced muscular power (25–75% 1RM) in the bench press and improved maximal strength and muscular power (25–90% 1RM) in the back squat by increasing muscle recruitment in resistance-trained men. Full article

Background: Sports performance indicators are mainly based on male athletes, highlighting the importance of portraying the female reality, particularly in rural contexts. This study aims to characterize sports performance indicators (body composition and physical fitness) of young Portuguese female athletes. Methods: A cross-sectional study was conducted with 124 girls (13.66 ± 1.93 years) participating in federated team sports in a rural region of Portugal. Body composition was assessed using bioelectrical impedance, and physical fitness was evaluated through vertical jump tests (countermovement jump and squat jump), sprint (20 m), agility (T-test), handgrip strength, and cardiovascular endurance (Yo-Yo IR1). Results: Volleyball players are taller; football and basketball players are heavier; football and volleyball players have more fat-free mass than handball players (p < 0.05). Body mass index and % body fat did not differ between sports (p > 0.05). Volleyball players performed better in the countermovement jump (F = 4.146, p = 0.008) and squat jump (F = 7.686, p < 0.001) when compared to basketball, football, and handball players. No differences were observed in the speed or cardiorespiratory endurance tests (p > 0.05). Conclusions: The results revealed that, despite some specific differences between sports, most physical fitness indicators did not differ significantly between sports after controlling for age, menarche, and training experience. These findings suggest that shared contextual limitations in rural regions may take precedence over sport-specific adaptations in the early stages of sports participation. Full article

Objectives: The aim of this study was to assess the safety and feasibility of resistance training (RT) in middle-aged and young individuals by examining cardiocirculatory and metabolic responses to squat performed under low and high external loads as per current exercise prescription guidelines. Methods: Eighteen RT-trained individuals (nine middle-aged individuals, including eight women who were equally distributed) performed a cycling incremental test for the determination of their maximal aerobic capacity and three sessions of RT, respectively, to determine their one repetition maximum (1RM) of squat and their physiological responses during different training protocols of squat with equal training loads (3 × 12 at 55% 1RM vs. 5 × 5 at 80% 1RM). Whole-body metabolic (oxygen update and blood lactate) and cardiocirculatory (heart rate and blood pressure) responses and rate of perceived exertion (RPE) were compared across age groups and % 1RM to determine the metabolic stimulus and cardiovascular strain imposed by this form of training. Results: Young and middle-aged individuals exhibited similar cardiocirculatory responses to RT, with the only exception being a higher diastolic response in the middle-aged group for both protocols (present also at rest). No difference was found between the two age groups in terms of metabolic response and RPE. 80% 1RM induced a similar cardiocirculatory response and a higher RPE but a lower metabolic response compared to 55% 1RM. Conclusions: While no difference in physiological responses was found between the groups, the lower-load and higher-repetition training scheme demonstrated better time efficiency, metabolic activation, and perceived effort with equivalent cardiocirculatory strain. These findings support the safety of RT and can guide practitioners in the design of training protocols. Full article

This study investigated the effects of a single-night sleep extension protocol on physical performance and cognitive function in physically active university students across different times of day. Using a within-subjects, counterbalanced crossover design, 24 physically active university students (17 males, 7 females; age: 22.7 ± 1.6 years) completed performance assessments under normal-sleep and sleep-extension conditions. Participants’ sleep was monitored via wrist actigraphy, and a comprehensive assessment battery comprising vertical jumps, Y-Balance tests, medicine-ball throws, 5 m shuttle-run tests, reaction-time tests, and digit-cancellation tests was administered at baseline (8 PM), morning (8 AM), and afternoon (4 PM). Sleep extension increased total sleep time by approximately 55 min (531.3 ± 56.8 min vs. 476.5 ± 64.2 min; p < 0.001, d = 0.91). Significant improvements were observed in 5 m shuttle-run performance at 8 AM (best distance: 102.8 ± 11.9 m vs. 93.3 ± 8.5 m, p < 0.001, d = 0.93; fatigue index: 13.1 ± 8.3% vs. 21.2 ± 9.5%, p < 0.001, d = 0.90), squat-jump heights (28.2 ± 8.0 cm vs. 26.3 ± 7.2 cm, p = 0.005, d = 0.25), simple reaction time (252.8 ± 55.3 ms vs. 296.4 ± 75.2 ms, p < 0.001, d = 0.66), and digit-cancellation performance (67.6 ± 12.6 vs. 63.0 ± 10.0 targets, p = 0.006, d = 0.40). Sleep extension significantly enhances both physical and cognitive performance in physically active individuals, with effects more pronounced during morning hours, partially attenuating typical circadian performance decline and establishing sleep extension as an effective, non-pharmacological strategy for optimizing performance capabilities. Full article

Low-load conditioning activity with blood flow restriction has been addressed as an efficient method to enhance an individual’s performance during their main exercise activity. However, the optimal degree of blood flow restriction remains unclear. Therefore, this study investigated the acute effects of low-load conditioning activity with different degrees of blood flow restriction on muscle strength, power, and perceived exertion. Twenty recreationally trained men (20.9 ± 2.3 years) participated in a randomized crossover design including three conditions: control, low-load blood flow restriction at 50%, and 75% of total arterial occlusion pressure. Participants performed squats (three sets of ten reps) followed by isokinetic assessments of the knee flexor and extensor performance at 7 and 10-min post-exercise. The session rating of perceived exertion (SRPE) was recorded 30 min after each session. No significant effects were observed for condition, time, or their interaction on peak torque, total work, or average power (p < 0.05). However, SRPE was significantly higher in the 75% BFR condition compared to both the 50% BFR and control conditions (p < 0.05), with no difference between the 50% BFR and control. These findings suggest that low-load conditioning activity with blood flow restriction does not acutely enhance neuromuscular performance. However, a higher degree of restriction increases perceived exertion. Full article

This study examined the effects of a short-term ballistic training program on neuromuscular performance and strength-deficit (SDef) in elite youth female soccer players. Twenty-two under-20 athletes completed a 4-week intervention during the pre-season phase, comprising 12 loaded and 8 unloaded ballistic training sessions performed at maximal intended velocity. Pre- and post-intervention assessments included vertical jumps (squat jump [SJ], countermovement jump [CMJ]), sprinting speed (5, 10, and 20 m), one-repetition maximum (1RM) and peak force (PF) in the half-squat (HS), and peak power and velocity during jump squats (JS) at 30% of 1RM. SDef was calculated as the percentage difference in PF between 1RM in the HS and 30% 1RM. Significant improvements were observed in SJ, CMJ, sprint speed, 1RM-strength, and bar-derived mechanical outputs (ES = 1.18–1.66; p < 0.05), with no significant changes in SDef. These results indicate that elite youth female soccer players can improve strength-, power-, and speed-related capacities without compromising force production at higher movement velocities (thus maintaining their SDef). The improvements observed likely reflect the combined effect of a high-frequency, velocity-oriented training approach and a concurrent reduction in traditional technical–tactical (i.e., soccer-specific) training volume. This is the first study to demonstrate that ballistic exercises alone—when properly structured—can enhance neuromuscular performance in female soccer players without increasing SDef. These findings provide practical guidance for practitioners aiming to optimize physical development in team-sport athletes without relying on heavier training loads or extended resistance training sessions—and, especially, without compromising their ability to apply force at higher velocities. Full article

This study aimed to examine the relationship between the eccentric utilization ratio (EUR) and sprint, change of direction (COD), change of direction deficit (CODD%), and vertical jump performance, including countermovement jump (CMJ) and squat jump (SJ). A total of 32 elite athletes (16 women and 16 men) participated. Performance was evaluated using force platforms and photocell timing systems during CMJ, SJ, 30 m sprint, and Pro-Agility tests. Pearson correlation and simple linear regression analyses were used to assess the relationships between EUR and performance variables. The results revealed that EUR was significantly associated with CMJ height (r = 0.587, p = 0.017) and 0–10 m sprint performance (r = 0.516, p = 0.041) in female athletes, whereas no significant relationships were found in males (r < 0.20, p > 0.05) for all performance variables. In contrast, strength–power metrics such as eccentric peak power (ECCPP), eccentric mean power (ECCMP), concentric mean power (CONMP), and peak power (PP) showed stronger associations with all performance variables, including COD, sprint segments, and jump tests. In conclusion, although EUR demonstrated limited predictive value particularly in male athletes directly measured strength–power variables appear to be more reliable indicators of athletic performance. These findings highlight the importance of prioritizing eccentric and concentric power outputs in performance assessment and individualized training strategies. Full article

Background and Objective: This study aimed to examine the possibility of using surface electromyography (sEMG) to aid in assessing the correctness of overhead deep squat performance. Electromyography signals were recorded for 20 athletes from the lower (rectus femoris (RF), vastus medialis (VM), biceps femoris (BF), and gluteus (GM)) and upper (deltoid (D), latissimus dorsi (L)) muscles. The sEMG signals were categorized into three groups based on physiotherapists’ evaluations of deep squat correctness. Methods: The raw sEMG signals were filtering at 10–250 Hz, and then the mean frequency, median frequency, and kurtosis were calculated. Next, the maximum excitation of the muscles expressed in percentage of maximum voluntary contraction (%MVC) and co-activation index (CAI) were estimated. To determine the muscle excitation level, the pulse interference filter and variance analysis of the sEMG signal derivative were applied. Next, analysis of variance (ANOVA) tests, that is, nonparametric Kruskal–Wallis and post hoc tests, were performed. Results: The parameter that most clearly differentiated the groups considered turned out to be %MVC. The statistically significant difference with a large effect size in the excitation of RF & GM (p = 0.0011) and VM & GM (p = 0.0002) in group 3, where the correctness of deep squat execution was the highest and ranged from 85% to 92%, was pointed out. With the decrease in the correctness of deep squat performance, an additional statistically significant difference appeared in the excitation of RF & BF and VM & BF for both groups 2 and 1, which was not present in group 3. However, in group 2, with the correctness of the deep squat execution at 62–77%, the statistically significant differences in muscle excitation found in group 3 were preserved, in contrast to group 1, with the lowest 23–54% correctness of the deep squat execution, where the statistical significance of these differences was not confirmed. Conclusions: The results indicate that sEMG can differentiate muscle activity and provide additional information for physiotherapists when assessing the correctness of deep squat performance. The proposed analysis can be used to evaluate the correctness of physical exercises when physiotherapist access is limited. Full article

Tests assessing physical qualities are regularly used in youth rugby league teams for various functions. However, the utility of such tests is under-explored in this population. In this way, tests are commonly examined in terms of how well they can differentiate performances between groups that are expected to differ and how they relate to outcomes in actual competitive contexts. Therefore, the purpose of this exploratory study was to investigate the discriminative validity and relationships to match performance metrics of frequently used tests to assess physical qualities in male, adolescent rugby league players. Anthropometric (standing height and body mass) and fitness-related (20 m linear sprint, 505-Agility Test, L-run Test, medicine ball throw, countermovement jump, one-repetition maximum back squat, bench press, and prone row tests, and Multistage Fitness Test) physical qualities were measured using common tests in 42 players (16.1 ± 1.3 years). Test outcomes were compared between players in different age and positional groups for discriminative validity analyses. Relationships between test outcomes and match performance metrics gathered via global positioning system and video analysis were also determined. Compared to younger players (14–15 years), older players (16–18 years) had significantly better fitness-related physical qualities (p < 0.05, d = −1.78–1.66), but similar anthropometric qualities (p > 0.05, d = −0.45–0.20). Significant, moderate correlations (p < 0.05, r = 0.56–0.70) were found between (1) one-repetition maximum (1-RM) back squat and relative (per min) high-speed running distance and maximum velocity in matches; (2) 20-m sprint time and relative total distance; (3) 505-Agility Test time and relative line breaks; and (4) height and relative unsuccessful tackles. Consequently, commonly used fitness-related tests demonstrate discriminative validity in detecting differences between age groups, with standing height and the 1-RM back squat showing promising utility given their associations with key match metrics in adolescent rugby league players. Full article

Background: This study aimed to compare the effects of an eight-week horizontal versus vertical vector resistance training program on swim start performance and lower-limb neuromuscular function in competitive swimmers. Methods: A total of 16 collegiate swimmers (14 males and 2 females; height: 176.3 ± 10 cm; body mass: 68.8 ± 10.3 kg; age: 20.5 ± 2.3 year) were assigned to either a horizontal vector training (HOR) or a vertical vector training (VER) group and completed an eight-week training program. Pre- and post-intervention assessments included flight time, flight distance, underwater speed, 15 m swim speed, 25 m swim speed, and force–time metrics within both concentric and eccentric phases of the countermovement jump and squat jumps. Results: No group or interaction effects were observed. However, time effects were found for flight distance (↑ 4.1–5.5%), flight time (↑ 6.2–12%), 15 m swim speed (↑ 0.3–0.7%), and jump performance. The HOR showed more favorable within-group trends in regards to swim start performance and concentric performance of countermovement and squat jumps. Moderate correlations (r = 0.450–0.476) were found between changes in concentric jump variables and 15 m swim speed. Conclusions: These results suggest that both vertical and horizontal vector resistance training can improve lower-limb neuromuscular performance and swim start performance. Full article

This study aimed to explore the independent and interactive effects of varying squat depths and movement speeds on dynamic postural stability during the Part the Wild Horse’s Mane (PWHM) movement. Thirteen male participants (age: 25.86 ± 1.35 years; height: 174.26 ± 6.09 cm; body mass: 68.64 ± 8.15 kg) performed the PWHM movement at three different squat heights, high squat (HS), middle squat (MS), low squat (LS), and two different speeds, fast and slow. Dynamic postural stability (DPSI) was assessed through the center-of-mass (CoM) trajectory and the center-of-pressure (CoP) trajectory. The analyses used two-factor repeated-measures ANOVA and statistical nonparametric mapping, with key metrics including anteroposterior stability (APSI), mediolateral stability (MLSI), vertical stability (VSI), DPSI indices, and the path lengths of the CoP and CoM. LS exhibited significantly greater CoP and CoM path lengths compared with MS and HS (p < 0.01). Furthermore, fast movements demonstrated higher VSI and DPSI than slow movements (p < 0.05). Tai Chi with different squat depths and speeds can affect postural stability. To reduce the fall risk, older adults and individuals with balance impairments should prioritize slower Tai Chi movements, particularly when using high squat postures. Full article

Objective: Most recreational gym-goers independently consume nutritional supplements (NSs) without physician advice and a personalized diet. The present study examines the preference for nutritional supplements (NSs) based on protein and amino acids of 218 recreational gym-goers (males and females aged 18–60). It also investigates the NS’s impact on resistance training (RT) performance. Methods: All participants (n = 218) were regular members of two gym centers in Oradea. Baseline data and information about daily diet and supplement preferences were obtained through face-to-face interviews. At the same time, RT performance was assessed by measuring 1RM in six exercises three times (W0, W4, and W8). Results: Our findings reveal that 24.3% of participants did not consume NSs, while the majority (75.6%, p < 0.05) used them to improve their physical condition; men were more likely to consume NSs than women (83.3% vs. 63.9%, p < 0.05). Gym-goers were grouped based on their NS consumption: L-carnitine, creatine, whey protein (WP), and triple combination; the non-supplemented group was the control. The combination substantially correlated with a balanced diet, 3001–3500 and >3500 calories/day; creatine was appreciably associated with 2001–2500 calories/day; L-carnitine was associated with 151–200 g protein/day, while control was considerably linked with a vegetarian diet and <1000 calorie/day (r > 0.900, p < 0.05). The results showed that almost all participants exhibited progressive muscle strength improvements. As an overview, 1RM substantially varied with NS consumed, body weight status, and gender (p < 0.0001), except for the pull-up count, which varied with NS and gender (p < 0.0001). Additionally, 1RM significantly varied with age (deadlift and pull-ups), daily protein consumption (back squats, biceps, and triceps), daily calories (back squats), and diet type (biceps, triceps, and pull-up exercises), p < 0.05. On the other hand, most NSs associated with RT exercises led to a general increase in body weight. Only L-carnitine decreased it. Conclusions: Resistance training records of recreational athletes are significantly influenced by age, gender, body weight status, NS type, and daily diet features (p < 0.05). Our findings highlight the essential role of professional guidance in nutritional supplementation associated with a suitable diet for optimal RT performance of recreational athletes. Full article